Probe: Maine pier collapsed 33 years beyond its expected life spanOct 2, 2015 02:28 PM
Courtesy U.S. Coast Guard
A large section of the collapsed pier at Eastport, Maine, litters the harbor.
The partial collapse of a Maine pier late last year was caused by the failure of internal components brought upon by decades of wear, according to federal investigators.
Roughly 200 feet of the Eastport pier’s older section collapsed at about 0200 on Dec. 4, 2014, damaging Eastport’s pilot boat and causing a minor leg injury to a caretaker aboard a 77-foot excursion vessel.
The incident led to the immediate shutdown of the pier located near downtown Eastport, the easternmost city in the U.S. The closure affected dozens of vessels that used the structure, including a fishing fleet, Coast Guard vessels and cruise ships.
“The National Transportation Safety Board (NTSB) determines that the probable cause of the collapse of the Eastport Port Authority breakwater pier was the failure of the lateral restraint system due to the structure’s long-term deterioration,” the agency said in a June report.
The L-shaped Eastport breakwater pier is owned by the city and operated by the Eastport Port Authority. The collapse occurred on the original 420-by-50-foot section, which was built in 1962 with an expected life span of 20 years. In 1985, a new pier section was added onto the existing structure, widening its entire length by 40 feet.
The section built in 1962 has an asphalt surface over a stone base surrounded by metal sheet pile and supported with wooden pilings. There were two rows of 2.75-inch-diameter horizontal tie rods and turnbuckles secured with steel wales used for bracing, according to the NTSB report.
The pilot boat Medric II is partially sunk and damaged.
Courtesy Capt. Bob Peacock
The collapse damaged the pilot boat Medric II and scallop dragger Double Trouble 2. The injury occurred aboard the excursion boat Ada C. Lore.
An engineering firm assessed the pier shortly after the incident to determine its overall structural integrity and to gauge the possibility of further damage. The company determined additional collapses were unlikely but warned the structure should not be used.
“The collapse was a result of failure of the lateral restraint system, which consists of two levels of tie rods arranged to resist lateral earth pressure. The exact failure mode could not be determined,” the company said, according to the NTSB report.
Prior pier inspections found significant structural deterioration since its original construction. The older pier section was about to be replaced with a new $15 million pier when it gave way. The new section will be added to the pier built in 1985.
Chris Gardner, executive director of the Eastport Port Authority, said the report’s findings did not come as a surprise.
“We knew that the deterioration of the facility was something that was going to be highlighted in any review,” he said, adding that the pier underwent major repairs several times over the years to extend its life.